The invention relates to a process for producing a peel or tear test specimen on a welded compound sheet or part thereof. The invention also relates to a device for carrying out the process.
The joining together of sheets by welding, in particular by mash seam or laser welding, is known. The assembly constituted by the joined sheets is known as a compound sheet. To complete the quality inspection, compound sheets or parts thereof with the welded seam are regularly removed from the production process and the strength of the weld is tested by destruction of the compound sheet. This is done by making cuts in one of the two joined sheets with sheet-metal shears to expose a tongue of the sheet material. This cutout tongue is bent over and gripped by means of a slotted key. The key is turned and the tongue is wound on to the key, towards the welded seam. The key is turned until the material is destroyed. From the position and surface features of the rupture point in the tongue or in the weld, the quality of the welded seam can be judged by visual inspection by a suitably trained person.
The process which has been outlined here has been found to have a number of shortcomings. First, the process is relatively time-consuming, as the cutting and bending operations are performed separately, by hand. Second, it appears that the results obtained from the manual tearing or peeling by means of the said key can vary very considerably depending on how it is performed by the operator. This can make the ensuing visual appraisal of the weld difficult.